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Posted by Tim Jackson on April 4, 2009, 11:05 pm
 
Eeyore wrote:

You're

The instantaneous mains frequency isn't rock solid.  The control system
keeps the long term *average* mains frequency rock solid so that
synchronous electric clocks stay in time, In the short term the
frequency drifts by anything up to a Hz or so.

The main reason is the time it takes mechanical generators to respond to
changes in overall load.

See, for example,
http://en.wikipedia.org/wiki/Mains_frequency

Tim Jackson

Posted by Eeyore on April 4, 2009, 11:11 pm
 


Tim Jackson wrote:


You're

Utter nonsense. Except in 3rd world countries maybe.

Graham


Posted by Ken on April 5, 2009, 6:47 am
 On Sun, 05 Apr 2009 00:11:34 +0100, Eeyore


yet,

You're

In Europe.
 

Posted by Eeyore on April 5, 2009, 10:25 pm
 

Ken wrote:


yet,

being

work. You're

I suggest you look up the regulations. You're talking out of your arse.

" In the continental European UCTE grid, the deviation between network phase
time and UTC
is calculated at 08:00 each day in a control center in Switzerland, and the
target
frequency is then adjusted by up to 0.02% from 50 Hz as needed, to ensure a
long-term
frequency average of exactly 36002450 cycles per day is maintained.[15] "
http://en.wikipedia.org/wiki/Utility_frequency#Long-term_stability_and_clock_synchronization

+/- 0.02% !

Graham


Posted by Tim Jackson on April 5, 2009, 11:21 pm
 Eeyore wrote:

yet,

You're

time and UTC

target

long-term

http://en.wikipedia.org/wiki/Utility_frequency#Long-term_stability_and_clock_synchronization

That's the TARGET frequency DAILY adjustment.  The ACTUAL frequency
varies on the ten-second time-scale with load changes, the generating
station local control systems adjust the power input to maintain the
daily average close to that target frequency.

Alistair Gunn posted in this thread that the UK statutory requirement is
plus or minus half a Hz, I didn't know that when I posted earlier, I
just knew from observations that it fluctuates over a range of something
approaching 1Hz over minutes under heavy load conditions, eg over the
notorious "tea-break" load spike.  Or it did several years ago when I
made those observations.

If you don't believe me go stick a frequency meter on your domestic
supply and see where it's at.  IIRC most of the time it was +/- 0.1Hz or
so, with occasional larger excursions.

Tim Jackson

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